Field of the Invention
Stereotaxis is a technique that has been developed and used for almost 80 years since Horsley and Clarke first invented the 3-D stereotactic machine; see Horsley et al, "On the Intrinsic Fibres of the Cerebellum, Its Nuclei and Its Efferent Tracts", Brain, 28, pp. 12-29 (1905); Horsley et al, "The Structure and Functions of the Cerebellum Examined by a New Method", Brain, 31, p. 45 (1908). Since this pioneering effort, many types of stereotactic equipment have been devised; see for example, Ingram et al, "Results of Stimulation of the Tegmentum with the Horsley-Clarke Stereotaxis Apparatus", Arch. Neurol. Psyciatrt., 28, 512-541 (1932); Leksell, "The Stereotactic Method and Radiosurgery of the Brain", Acta Chir. Scand., 102, 315-319 (1951); Barcia-Salorio et al, "Tomography in Stereotaxis: A New Stereoencephalotome Designed for this Purpose", Acta Neurochir. Suppl., 24, 77-83 (1977). In the early practice of stereotactic surgery the road map to the target was provided by conventional x-ray pictures that were often enhanced by contrast material techniques.
In the late 1970s, the integration of stereotaxis with computerized tomographic (CT) scanning provided a much more powerful tool for surgeons. This technique used high-resolution axial two-dimensional pictures to guide the probe to the target accurately. Several groups have developed CT-aided stereotactic head frames for intracranial operations; see Brown, "A Computerized Tomography-Computer Graphics Approach to Stereotactic Localization", Journal of Neurosurgery, 50, 715-720 (June 1979); Brown, "A Stereotactic Head Frame for Use with CT Body Scanners", Investigative Radiology, 14, 300-304 (July-August 1979); Brown et al, "Stereotactic Frame and Computer Software for CT-Directed Neurosurgical Locations", Investigative Radiology, 15, 308-312 (July-August 1980); Second Annual Symposium on Parkinson's Disease, Journal of Neurosurgery, 24, 430-481 (1966); Shao et al, "A New CT-Aided Stereotactic Neurosurgery Technique", to be published in IEEE Trans. on Biomedical Engineering. The brain is ideally suited for such procedures because of the availability of rigid skull fixation and the absence of physiologic motion.
Recently, a CT-aided stereotactic body frame was announced by Siemens. An independent parallel effort in this direction has also been tested; Lightfoot et al, "A Computer Assisted Stereotactic Procedure System for CT Scanners"; submitted to IEEE Trans. on Biomedical Engineering. These approaches extended precision stereotaxis to the whole human body.
Stereotactic neurosurgery is a technique for guiding the tip of a probe or other delicate instrument to a predetermined point in the nervous system without direct viewing of the surgical site. Referencing is provided by a stereotactic landmark, for example a head frame or brace into which the patient's head is placed. Reference marks along two axes are used to locate and position surgical instruments. To visualize the interior of the skull, a CT scan is used, providing two-dimentional, high-resolution, axial pictures that show detailed soft-tissued anatomy inside the cranial vault and the spinal cord.
Until now, all previous stereotactic techniques, not just those used in neurosurgery, involved the use of some type of stereotactic "frame." However, the use of a frame presents the surgeon with several problems. The manual reading, setting and adjustment of the frame parameters is a time-consuming process, error prone when frequent maneuvers are required, and thus makes frequent trajectory modifications difficult. A motorized frame could help solve this problem, but such a system tends to be heavy and bulky. A frame is usually designed only for the head or body. Although a frame intended for application to both the head and body has been designed, see the Lightfoot et al article mentioned above, to date its performance has not been satisfactory.
The fixed radius of a frame arch also lacks the flexibility that surgeons prefer. For example, the surgeon often wishes to place the probe holder as close to the patient as possible, which requires a small arch. But if one builds a frame with the required small arch, it cannot be used with an oversized patient. Further, each frame, depending on its structure and design, has unreachable corners. On occasion, the desired trajectory is within one of these forbidden zones of the frame. In prior frames of this type, the physical difficulties of reading the CT scan data and setting appropriate parameters on the frame could lead to human errors. Finally, such frame structures hamper the surgeon's view of the patient, making some surgical procedures quite difficult, and a frame between surgeon and patient can in general be an awkward arrangement.
There is thus a need to replace hitherto-employed stereotactic frames with other means which will permit more widespread and convenient use of stereotactic surgery in a greater variety of procedures useable on larger numbers of human and veterinary patients.
Accordingly it is an object of this invention to provide a novel apparatus and method for conducting stereotactic surgery.
It is also an object of this invention to provide a novel apparatus and method for conducting stereotactic surgery and related procedures of all types which dispense with the need for a stereotactic frame.
A further object of this invention is to provide a novel apparatus and method for conducting stereotactic surgery and related procedures of all types which provide the surgeon with a flexible, speedy and accurate means of conducting such procedures, thus permitting increasingly sophisticated stereotactic procedures to be conducted.
These and other objects, as well as the nature, scope and utilization of the invention, will become readily apparent to those skilled in the art from the following description, the drawings, and the appended claims.